Various theories have been proposed with respect to a cause of ulcer in human. In particular, it has been elucidated that stress, taking of non-steroidal anti-inflammatory drugs for curing rheumatic diseases, and the like are closely related to ulcer formation, mainly due to relatively excess gastric or duodenal acid secretion. Accordingly, it is important to suppress the acid secretion in order to prevent ulcer formation and to cure it.
On the other hand, it has been considered that Helicobacter pyroli, which is a rod normally existing in stomach, generates ammonia due to its strong urease activity, thereby inducing ulcer. Since it persistently lives within mucus and mucosa, it becomes the greatest cause for recurrence of ulcer. Accordingly, it has been considered that the recurrence of ulcer can be prevented if this bacterium is sterilized.
Though various kinds of medicaments for curing ulcer have been conventionally developed, few medicaments have been known to have an effect for preventing stress ulcers from generating or an antibacterial activity against Helicobacter pyroli.